_ DIASTETHUS. 223 
- Sect. CENTRINIDES *, 
Centrinides, Lacordaire. 
DIASTETHUS. 
Diastethus, Pascoe, Ann. & Mag. Nat. Hist. (6) iv. pp. 323, 327 (1889). 
Pascoe gives Centrinus tumidus, Boh., as the type of this genus, which will also have 
to include a large number of Central- and S.-American forms, such as C. parellinus, 
cyanipes, mexicanus, falcatus, ater, Boh., &c. Some of them are metallic (resembling 
Eurhinus and certain forms referred to Cylindrocerus by Schénherr), others black, 
castaneous, or ferruginous. The non-metallic species have the facies of a Diorymerus, 
but differ from that genus in the imperfectly sulcate, toothed femora, the less excavate 
pro-, meso-, and metasternum, &c. In well-developed males of D. aztecus and D. ater 
the prosternum is not only armed with two spines, but has a deep, circular cavity 
between them (as in Pascoe’s genus Camelodes); no importance, however, can be attached 
to this character, as the spines and cavity are sometimes wholly wanting in individuals 
of minor development of the same species. The various forms referred to Diastethus 
agree in the following characters :-— 
Mandibles almost straight on their inner edge, sometimes toothed on their outer edge beneath; rostrum more 
or less elongate, strongly arcuate; antennal club ovate or oblong-ovate, with distinct sutures ; prothorax 
narrow and tubulate in front, bisinuate at the base, often gibbous on the disc, without ocular lobes ; 
scutellum transverse; elytra more or less triangular; pygidium hidden; anterior coxe moderately 
distant; prosternum more or less sulcate down the middle, in the ¢ sometimes armed with two spines or 
tubercles, and with a circular excavation between them ; metasternum binodose or not in front; femora 
dentate and more or less sulcate towards the apex beneath ; tarsal claws approximate or subconnate at the 
base ; body rhomboidal or subrhomboidal, polished or alutaceous, glabrous above, the scutellum sometimes 
squamose. 
a. Metasternum binodose and rather prominent in front; femora bidentate ; 
intermediate tibie with a long spine on outer edge; prosterna! sulcus - 
shallow: body metallic, polished, the under surface with dense patches of 
whitish scales 2. 0. 0. eee ee ee 
b. Metasternum flattened, not prominent in front. 
a', Mandibles without tooth at the sides beneath. 
a, All the femora uni- or hidentate. 
a’. Tibize rounded at the base externally. 
a‘, Body metallic, polished, the under surface with dense patches of 
Species 1. 
whitish scales. . . . ~ . Species 2. 
b'. Body metallic, finely alutaceous, the under surface without patches 
of scales. . . . ss Species 3. 
* The whole of the members of this section have not yet been studied by me, and the term is only used 
here for convenience of arrangement. The Centrinides, however, it may be noted, probably include nearly all 
the Barids armed with prosternal spines in the male; but this character, unfortunately, cannot always be 
relied upon, as the spines vary in development in the same species, and are sometimes wanting. The 
scutellum, too, is free and the pygidium (with rare exceptions) covered in both sexes. 
